builtin/revert.c

   1 #include "cache.h"
   2 #include "builtin.h"
   3 #include "object.h"
   4 #include "commit.h"
   5 #include "tag.h"
   6 #include "run-command.h"
   7 #include "exec_cmd.h"
   8 #include "utf8.h"
   9 #include "parse-options.h"
  10 #include "cache-tree.h"
  11 #include "diff.h"
  12 #include "revision.h"
  13 #include "rerere.h"
  14 #include "merge-recursive.h"
  15 #include "refs.h"
  16 #include "dir.h"
  17 #include "sequencer.h"
  18
  19 /*
  20  * This implements the builtins revert and cherry-pick.
  21  *
  22  * Copyright (c) 2007 Johannes E. Schindelin
  23  *
  24  * Based on git-revert.sh, which is
  25  *
  26  * Copyright (c) 2005 Linus Torvalds
  27  * Copyright (c) 2005 Junio C Hamano
  28  */
  29
  30 static const char * const revert_usage[] = {
  31         "git revert [options] <commit-ish>",
  32         "git revert <subcommand>",
  33         NULL
  34 };
  35
  36 static const char * const cherry_pick_usage[] = {
  37         "git cherry-pick [options] <commit-ish>",
  38         "git cherry-pick <subcommand>",
  39         NULL
  40 };
  41
  42 enum replay_action { REVERT, CHERRY_PICK };
  43 enum replay_subcommand { REPLAY_NONE, REPLAY_RESET };
  44
  45 struct replay_opts {
  46         enum replay_action action;
  47         enum replay_subcommand subcommand;
  48
  49         /* Boolean options */
  50         int edit;
  51         int record_origin;
  52         int no_commit;
  53         int signoff;
  54         int allow_ff;
  55         int allow_rerere_auto;
  56
  57         int mainline;
  58         int commit_argc;
  59         const char **commit_argv;
  60
  61         /* Merge strategy */
  62         const char *strategy;
  63         const char **xopts;
  64         size_t xopts_nr, xopts_alloc;
  65 };
  66
  67 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
  68
  69 static void fatal(const char *advice, ...)
  70 {
  71         va_list params;
  72
  73         va_start(params, advice);
  74         vreportf("fatal: ", advice, params);
  75         va_end(params);
  76 }
  77
  78 static const char *action_name(const struct replay_opts *opts)
  79 {
  80         return opts->action == REVERT ? "revert" : "cherry-pick";
  81 }
  82
  83 static char *get_encoding(const char *message);
  84
  85 static const char * const *revert_or_cherry_pick_usage(struct replay_opts *opts)
  86 {
  87         return opts->action == REVERT ? revert_usage : cherry_pick_usage;
  88 }
  89
  90 static int option_parse_x(const struct option *opt,
  91                           const char *arg, int unset)
  92 {
  93         struct replay_opts **opts_ptr = opt->value;
  94         struct replay_opts *opts = *opts_ptr;
  95
  96         if (unset)
  97                 return 0;
  98
  99         ALLOC_GROW(opts->xopts, opts->xopts_nr + 1, opts->xopts_alloc);
 100         opts->xopts[opts->xopts_nr++] = xstrdup(arg);
 101         return 0;
 102 }
 103
 104 static void verify_opt_compatible(const char *me, const char *base_opt, ...)
 105 {
 106         const char *this_opt;
 107         va_list ap;
 108
 109         va_start(ap, base_opt);
 110         while ((this_opt = va_arg(ap, const char *))) {
 111                 if (va_arg(ap, int))
 112                         break;
 113         }
 114         va_end(ap);
 115
 116         if (this_opt)
 117                 die(_("%s: %s cannot be used with %s"), me, this_opt, base_opt);
 118 }
 119
 120 static void parse_args(int argc, const char **argv, struct replay_opts *opts)
 121 {
 122         const char * const * usage_str = revert_or_cherry_pick_usage(opts);
 123         const char *me = action_name(opts);
 124         int noop;
 125         int reset = 0;
 126         struct option options[] = {
 127                 OPT_BOOLEAN(0, "reset", &reset, "forget the current operation"),
 128                 OPT_BOOLEAN('n', "no-commit", &opts->no_commit, "don't automatically commit"),
 129                 OPT_BOOLEAN('e', "edit", &opts->edit, "edit the commit message"),
 130                 { OPTION_BOOLEAN, 'r', NULL, &noop, NULL, "no-op (backward compatibility)",
 131                   PARSE_OPT_NOARG | PARSE_OPT_HIDDEN, NULL, 0 },
 132                 OPT_BOOLEAN('s', "signoff", &opts->signoff, "add Signed-off-by:"),
 133                 OPT_INTEGER('m', "mainline", &opts->mainline, "parent number"),
 134                 OPT_RERERE_AUTOUPDATE(&opts->allow_rerere_auto),
 135                 OPT_STRING(0, "strategy", &opts->strategy, "strategy", "merge strategy"),
 136                 OPT_CALLBACK('X', "strategy-option", &opts, "option",
 137                         "option for merge strategy", option_parse_x),
 138                 OPT_END(),
 139                 OPT_END(),
 140                 OPT_END(),
 141         };
 142
 143         if (opts->action == CHERRY_PICK) {
 144                 struct option cp_extra[] = {
 145                         OPT_BOOLEAN('x', NULL, &opts->record_origin, "append commit name"),
 146                         OPT_BOOLEAN(0, "ff", &opts->allow_ff, "allow fast-forward"),
 147                         OPT_END(),
 148                 };
 149                 if (parse_options_concat(options, ARRAY_SIZE(options), cp_extra))
 150                         die(_("program error"));
 151         }
 152
 153         opts->commit_argc = parse_options(argc, argv, NULL, options, usage_str,
 154                                         PARSE_OPT_KEEP_ARGV0 |
 155                                         PARSE_OPT_KEEP_UNKNOWN);
 156
 157         /* Set the subcommand */
 158         if (reset)
 159                 opts->subcommand = REPLAY_RESET;
 160         else
 161                 opts->subcommand = REPLAY_NONE;
 162
 163         /* Check for incompatible command line arguments */
 164         if (opts->subcommand == REPLAY_RESET) {
 165                 verify_opt_compatible(me, "--reset",
 166                                 "--no-commit", opts->no_commit,
 167                                 "--signoff", opts->signoff,
 168                                 "--mainline", opts->mainline,
 169                                 "--strategy", opts->strategy ? 1 : 0,
 170                                 "--strategy-option", opts->xopts ? 1 : 0,
 171                                 "-x", opts->record_origin,
 172                                 "--ff", opts->allow_ff,
 173                                 NULL);
 174         }
 175
 176         else if (opts->commit_argc < 2)
 177                 usage_with_options(usage_str, options);
 178
 179         if (opts->allow_ff)
 180                 verify_opt_compatible(me, "--ff",
 181                                 "--signoff", opts->signoff,
 182                                 "--no-commit", opts->no_commit,
 183                                 "-x", opts->record_origin,
 184                                 "--edit", opts->edit,
 185                                 NULL);
 186         opts->commit_argv = argv;
 187 }
 188
 189 struct commit_message {
 190         char *parent_label;
 191         const char *label;
 192         const char *subject;
 193         char *reencoded_message;
 194         const char *message;
 195 };
 196
 197 static int get_message(struct commit *commit, struct commit_message *out)
 198 {
 199         const char *encoding;
 200         const char *abbrev, *subject;
 201         int abbrev_len, subject_len;
 202         char *q;
 203
 204         if (!commit->buffer)
 205                 return -1;
 206         encoding = get_encoding(commit->buffer);
 207         if (!encoding)
 208                 encoding = "UTF-8";
 209         if (!git_commit_encoding)
 210                 git_commit_encoding = "UTF-8";
 211
 212         out->reencoded_message = NULL;
 213         out->message = commit->buffer;
 214         if (strcmp(encoding, git_commit_encoding))
 215                 out->reencoded_message = reencode_string(commit->buffer,
 216                                         git_commit_encoding, encoding);
 217         if (out->reencoded_message)
 218                 out->message = out->reencoded_message;
 219
 220         abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
 221         abbrev_len = strlen(abbrev);
 222
 223         subject_len = find_commit_subject(out->message, &subject);
 224
 225         out->parent_label = xmalloc(strlen("parent of ") + abbrev_len +
 226                               strlen("... ") + subject_len + 1);
 227         q = out->parent_label;
 228         q = mempcpy(q, "parent of ", strlen("parent of "));
 229         out->label = q;
 230         q = mempcpy(q, abbrev, abbrev_len);
 231         q = mempcpy(q, "... ", strlen("... "));
 232         out->subject = q;
 233         q = mempcpy(q, subject, subject_len);
 234         *q = '\0';
 235         return 0;
 236 }
 237
 238 static void free_message(struct commit_message *msg)
 239 {
 240         free(msg->parent_label);
 241         free(msg->reencoded_message);
 242 }
 243
 244 static char *get_encoding(const char *message)
 245 {
 246         const char *p = message, *eol;
 247
 248         while (*p && *p != '\n') {
 249                 for (eol = p + 1; *eol && *eol != '\n'; eol++)
 250                         ; /* do nothing */
 251                 if (!prefixcmp(p, "encoding ")) {
 252                         char *result = xmalloc(eol - 8 - p);
 253                         strlcpy(result, p + 9, eol - 8 - p);
 254                         return result;
 255                 }
 256                 p = eol;
 257                 if (*p == '\n')
 258                         p++;
 259         }
 260         return NULL;
 261 }
 262
 263 static void write_cherry_pick_head(struct commit *commit)
 264 {
 265         int fd;
 266         struct strbuf buf = STRBUF_INIT;
 267
 268         strbuf_addf(&buf, "%s\n", sha1_to_hex(commit->object.sha1));
 269
 270         fd = open(git_path("CHERRY_PICK_HEAD"), O_WRONLY | O_CREAT, 0666);
 271         if (fd < 0)
 272                 die_errno(_("Could not open '%s' for writing"),
 273                           git_path("CHERRY_PICK_HEAD"));
 274         if (write_in_full(fd, buf.buf, buf.len) != buf.len || close(fd))
 275                 die_errno(_("Could not write to '%s'"), git_path("CHERRY_PICK_HEAD"));
 276         strbuf_release(&buf);
 277 }
 278
 279 static void print_advice(void)
 280 {
 281         char *msg = getenv("GIT_CHERRY_PICK_HELP");
 282
 283         if (msg) {
 284                 fprintf(stderr, "%s\n", msg);
 285                 /*
 286                  * A conflict has occured but the porcelain
 287                  * (typically rebase --interactive) wants to take care
 288                  * of the commit itself so remove CHERRY_PICK_HEAD
 289                  */
 290                 unlink(git_path("CHERRY_PICK_HEAD"));
 291                 return;
 292         }
 293
 294         advise("after resolving the conflicts, mark the corrected paths");
 295         advise("with 'git add <paths>' or 'git rm <paths>'");
 296         advise("and commit the result with 'git commit'");
 297 }
 298
 299 static void write_message(struct strbuf *msgbuf, const char *filename)
 300 {
 301         static struct lock_file msg_file;
 302
 303         int msg_fd = hold_lock_file_for_update(&msg_file, filename,
 304                                                LOCK_DIE_ON_ERROR);
 305         if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
 306                 die_errno(_("Could not write to %s."), filename);
 307         strbuf_release(msgbuf);
 308         if (commit_lock_file(&msg_file) < 0)
 309                 die(_("Error wrapping up %s"), filename);
 310 }
 311
 312 static struct tree *empty_tree(void)
 313 {
 314         struct tree *tree = xcalloc(1, sizeof(struct tree));
 315
 316         tree->object.parsed = 1;
 317         tree->object.type = OBJ_TREE;
 318         pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
 319         return tree;
 320 }
 321
 322 static NORETURN void die_dirty_index(struct replay_opts *opts)
 323 {
 324         if (read_cache_unmerged()) {
 325                 die_resolve_conflict(action_name(opts));
 326         } else {
 327                 if (advice_commit_before_merge) {
 328                         if (opts->action == REVERT)
 329                                 die(_("Your local changes would be overwritten by revert.\n"
 330                                           "Please, commit your changes or stash them to proceed."));
 331                         else
 332                                 die(_("Your local changes would be overwritten by cherry-pick.\n"
 333                                           "Please, commit your changes or stash them to proceed."));
 334                 } else {
 335                         if (opts->action == REVERT)
 336                                 die(_("Your local changes would be overwritten by revert.\n"));
 337                         else
 338                                 die(_("Your local changes would be overwritten by cherry-pick.\n"));
 339                 }
 340         }
 341 }
 342
 343 static int fast_forward_to(const unsigned char *to, const unsigned char *from)
 344 {
 345         struct ref_lock *ref_lock;
 346
 347         read_cache();
 348         if (checkout_fast_forward(from, to))
 349                 exit(1); /* the callee should have complained already */
 350         ref_lock = lock_any_ref_for_update("HEAD", from, 0);
 351         return write_ref_sha1(ref_lock, to, "cherry-pick");
 352 }
 353
 354 static int do_recursive_merge(struct commit *base, struct commit *next,
 355                               const char *base_label, const char *next_label,
 356                               unsigned char *head, struct strbuf *msgbuf,
 357                               struct replay_opts *opts)
 358 {
 359         struct merge_options o;
 360         struct tree *result, *next_tree, *base_tree, *head_tree;
 361         int clean, index_fd;
 362         const char **xopt;
 363         static struct lock_file index_lock;
 364
 365         index_fd = hold_locked_index(&index_lock, 1);
 366
 367         read_cache();
 368
 369         init_merge_options(&o);
 370         o.ancestor = base ? base_label : "(empty tree)";
 371         o.branch1 = "HEAD";
 372         o.branch2 = next ? next_label : "(empty tree)";
 373
 374         head_tree = parse_tree_indirect(head);
 375         next_tree = next ? next->tree : empty_tree();
 376         base_tree = base ? base->tree : empty_tree();
 377
 378         for (xopt = opts->xopts; xopt != opts->xopts + opts->xopts_nr; xopt++)
 379                 parse_merge_opt(&o, *xopt);
 380
 381         clean = merge_trees(&o,
 382                             head_tree,
 383                             next_tree, base_tree, &result);
 384
 385         if (active_cache_changed &&
 386             (write_cache(index_fd, active_cache, active_nr) ||
 387              commit_locked_index(&index_lock)))
 388                 /* TRANSLATORS: %s will be "revert" or "cherry-pick" */
 389                 die(_("%s: Unable to write new index file"), action_name(opts));
 390         rollback_lock_file(&index_lock);
 391
 392         if (!clean) {
 393                 int i;
 394                 strbuf_addstr(msgbuf, "\nConflicts:\n\n");
 395                 for (i = 0; i < active_nr;) {
 396                         struct cache_entry *ce = active_cache[i++];
 397                         if (ce_stage(ce)) {
 398                                 strbuf_addch(msgbuf, '\t');
 399                                 strbuf_addstr(msgbuf, ce->name);
 400                                 strbuf_addch(msgbuf, '\n');
 401                                 while (i < active_nr && !strcmp(ce->name,
 402                                                 active_cache[i]->name))
 403                                         i++;
 404                         }
 405                 }
 406         }
 407
 408         return !clean;
 409 }
 410
 411 /*
 412  * If we are cherry-pick, and if the merge did not result in
 413  * hand-editing, we will hit this commit and inherit the original
 414  * author date and name.
 415  * If we are revert, or if our cherry-pick results in a hand merge,
 416  * we had better say that the current user is responsible for that.
 417  */
 418 static int run_git_commit(const char *defmsg, struct replay_opts *opts)
 419 {
 420         /* 6 is max possible length of our args array including NULL */
 421         const char *args[6];
 422         int i = 0;
 423
 424         args[i++] = "commit";
 425         args[i++] = "-n";
 426         if (opts->signoff)
 427                 args[i++] = "-s";
 428         if (!opts->edit) {
 429                 args[i++] = "-F";
 430                 args[i++] = defmsg;
 431         }
 432         args[i] = NULL;
 433
 434         return run_command_v_opt(args, RUN_GIT_CMD);
 435 }
 436
 437 static int do_pick_commit(struct commit *commit, struct replay_opts *opts)
 438 {
 439         unsigned char head[20];
 440         struct commit *base, *next, *parent;
 441         const char *base_label, *next_label;
 442         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 443         char *defmsg = NULL;
 444         struct strbuf msgbuf = STRBUF_INIT;
 445         int res;
 446
 447         if (opts->no_commit) {
 448                 /*
 449                  * We do not intend to commit immediately.  We just want to
 450                  * merge the differences in, so let's compute the tree
 451                  * that represents the "current" state for merge-recursive
 452                  * to work on.
 453                  */
 454                 if (write_cache_as_tree(head, 0, NULL))
 455                         die (_("Your index file is unmerged."));
 456         } else {
 457                 if (get_sha1("HEAD", head))
 458                         die (_("You do not have a valid HEAD"));
 459                 if (index_differs_from("HEAD", 0))
 460                         die_dirty_index(opts);
 461         }
 462         discard_cache();
 463
 464         if (!commit->parents) {
 465                 parent = NULL;
 466         }
 467         else if (commit->parents->next) {
 468                 /* Reverting or cherry-picking a merge commit */
 469                 int cnt;
 470                 struct commit_list *p;
 471
 472                 if (!opts->mainline)
 473                         die(_("Commit %s is a merge but no -m option was given."),
 474                             sha1_to_hex(commit->object.sha1));
 475
 476                 for (cnt = 1, p = commit->parents;
 477                      cnt != opts->mainline && p;
 478                      cnt++)
 479                         p = p->next;
 480                 if (cnt != opts->mainline || !p)
 481                         die(_("Commit %s does not have parent %d"),
 482                             sha1_to_hex(commit->object.sha1), opts->mainline);
 483                 parent = p->item;
 484         } else if (0 < opts->mainline)
 485                 die(_("Mainline was specified but commit %s is not a merge."),
 486                     sha1_to_hex(commit->object.sha1));
 487         else
 488                 parent = commit->parents->item;
 489
 490         if (opts->allow_ff && parent && !hashcmp(parent->object.sha1, head))
 491                 return fast_forward_to(commit->object.sha1, head);
 492
 493         if (parent && parse_commit(parent) < 0)
 494                 /* TRANSLATORS: The first %s will be "revert" or
 495                    "cherry-pick", the second %s a SHA1 */
 496                 die(_("%s: cannot parse parent commit %s"),
 497                     action_name(opts), sha1_to_hex(parent->object.sha1));
 498
 499         if (get_message(commit, &msg) != 0)
 500                 die(_("Cannot get commit message for %s"),
 501                                 sha1_to_hex(commit->object.sha1));
 502
 503         /*
 504          * "commit" is an existing commit.  We would want to apply
 505          * the difference it introduces since its first parent "prev"
 506          * on top of the current HEAD if we are cherry-pick.  Or the
 507          * reverse of it if we are revert.
 508          */
 509
 510         defmsg = git_pathdup("MERGE_MSG");
 511
 512         if (opts->action == REVERT) {
 513                 base = commit;
 514                 base_label = msg.label;
 515                 next = parent;
 516                 next_label = msg.parent_label;
 517                 strbuf_addstr(&msgbuf, "Revert \"");
 518                 strbuf_addstr(&msgbuf, msg.subject);
 519                 strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
 520                 strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 521
 522                 if (commit->parents && commit->parents->next) {
 523                         strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
 524                         strbuf_addstr(&msgbuf, sha1_to_hex(parent->object.sha1));
 525                 }
 526                 strbuf_addstr(&msgbuf, ".\n");
 527         } else {
 528                 const char *p;
 529
 530                 base = parent;
 531                 base_label = msg.parent_label;
 532                 next = commit;
 533                 next_label = msg.label;
 534
 535                 /*
 536                  * Append the commit log message to msgbuf; it starts
 537                  * after the tree, parent, author, committer
 538                  * information followed by "\n\n".
 539                  */
 540                 p = strstr(msg.message, "\n\n");
 541                 if (p) {
 542                         p += 2;
 543                         strbuf_addstr(&msgbuf, p);
 544                 }
 545
 546                 if (opts->record_origin) {
 547                         strbuf_addstr(&msgbuf, "(cherry picked from commit ");
 548                         strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 549                         strbuf_addstr(&msgbuf, ")\n");
 550                 }
 551                 if (!opts->no_commit)
 552                         write_cherry_pick_head(commit);
 553         }
 554
 555         if (!opts->strategy || !strcmp(opts->strategy, "recursive") || opts->action == REVERT) {
 556                 res = do_recursive_merge(base, next, base_label, next_label,
 557                                          head, &msgbuf, opts);
 558                 write_message(&msgbuf, defmsg);
 559         } else {
 560                 struct commit_list *common = NULL;
 561                 struct commit_list *remotes = NULL;
 562
 563                 write_message(&msgbuf, defmsg);
 564
 565                 commit_list_insert(base, &common);
 566                 commit_list_insert(next, &remotes);
 567                 res = try_merge_command(opts->strategy, opts->xopts_nr, opts->xopts,
 568                                         common, sha1_to_hex(head), remotes);
 569                 free_commit_list(common);
 570                 free_commit_list(remotes);
 571         }
 572
 573         if (res) {
 574                 error(opts->action == REVERT
 575                       ? _("could not revert %s... %s")
 576                       : _("could not apply %s... %s"),
 577                       find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV),
 578                       msg.subject);
 579                 print_advice();
 580                 rerere(opts->allow_rerere_auto);
 581         } else {
 582                 if (!opts->no_commit)
 583                         res = run_git_commit(defmsg, opts);
 584         }
 585
 586         free_message(&msg);
 587         free(defmsg);
 588
 589         return res;
 590 }
 591
 592 static void prepare_revs(struct rev_info *revs, struct replay_opts *opts)
 593 {
 594         int argc;
 595
 596         init_revisions(revs, NULL);
 597         revs->no_walk = 1;
 598         if (opts->action != REVERT)
 599                 revs->reverse = 1;
 600
 601         argc = setup_revisions(opts->commit_argc, opts->commit_argv, revs, NULL);
 602         if (argc > 1)
 603                 usage(*revert_or_cherry_pick_usage(opts));
 604
 605         if (prepare_revision_walk(revs))
 606                 die(_("revision walk setup failed"));
 607
 608         if (!revs->commits)
 609                 die(_("empty commit set passed"));
 610 }
 611
 612 static void read_and_refresh_cache(struct replay_opts *opts)
 613 {
 614         static struct lock_file index_lock;
 615         int index_fd = hold_locked_index(&index_lock, 0);
 616         if (read_index_preload(&the_index, NULL) < 0)
 617                 die(_("git %s: failed to read the index"), action_name(opts));
 618         refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL, NULL);
 619         if (the_index.cache_changed) {
 620                 if (write_index(&the_index, index_fd) ||
 621                     commit_locked_index(&index_lock))
 622                         die(_("git %s: failed to refresh the index"), action_name(opts));
 623         }
 624         rollback_lock_file(&index_lock);
 625 }
 626
 627 /*
 628  * Append a commit to the end of the commit_list.
 629  *
 630  * next starts by pointing to the variable that holds the head of an
 631  * empty commit_list, and is updated to point to the "next" field of
 632  * the last item on the list as new commits are appended.
 633  *
 634  * Usage example:
 635  *
 636  *     struct commit_list *list;
 637  *     struct commit_list **next = &list;
 638  *
 639  *     next = commit_list_append(c1, next);
 640  *     next = commit_list_append(c2, next);
 641  *     assert(commit_list_count(list) == 2);
 642  *     return list;
 643  */
 644 struct commit_list **commit_list_append(struct commit *commit,
 645                                         struct commit_list **next)
 646 {
 647         struct commit_list *new = xmalloc(sizeof(struct commit_list));
 648         new->item = commit;
 649         *next = new;
 650         new->next = NULL;
 651         return &new->next;
 652 }
 653
 654 static int format_todo(struct strbuf *buf, struct commit_list *todo_list,
 655                 struct replay_opts *opts)
 656 {
 657         struct commit_list *cur = NULL;
 658         struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
 659         const char *sha1_abbrev = NULL;
 660         const char *action_str = opts->action == REVERT ? "revert" : "pick";
 661
 662         for (cur = todo_list; cur; cur = cur->next) {
 663                 sha1_abbrev = find_unique_abbrev(cur->item->object.sha1, DEFAULT_ABBREV);
 664                 if (get_message(cur->item, &msg))
 665                         return error(_("Cannot get commit message for %s"), sha1_abbrev);
 666                 strbuf_addf(buf, "%s %s %s\n", action_str, sha1_abbrev, msg.subject);
 667         }
 668         return 0;
 669 }
 670
 671 static void walk_revs_populate_todo(struct commit_list **todo_list,
 672                                 struct replay_opts *opts)
 673 {
 674         struct rev_info revs;
 675         struct commit *commit;
 676         struct commit_list **next;
 677
 678         prepare_revs(&revs, opts);
 679
 680         next = todo_list;
 681         while ((commit = get_revision(&revs)))
 682                 next = commit_list_append(commit, next);
 683 }
 684
 685 static int create_seq_dir(void)
 686 {
 687         const char *seq_dir = git_path(SEQ_DIR);
 688
 689         if (file_exists(seq_dir))
 690                 return error(_("%s already exists."), seq_dir);
 691         else if (mkdir(seq_dir, 0777) < 0)
 692                 die_errno(_("Could not create sequencer directory '%s'."), seq_dir);
 693         return 0;
 694 }
 695
 696 static void save_head(const char *head)
 697 {
 698         const char *head_file = git_path(SEQ_HEAD_FILE);
 699         static struct lock_file head_lock;
 700         struct strbuf buf = STRBUF_INIT;
 701         int fd;
 702
 703         fd = hold_lock_file_for_update(&head_lock, head_file, LOCK_DIE_ON_ERROR);
 704         strbuf_addf(&buf, "%s\n", head);
 705         if (write_in_full(fd, buf.buf, buf.len) < 0)
 706                 die_errno(_("Could not write to %s."), head_file);
 707         if (commit_lock_file(&head_lock) < 0)
 708                 die(_("Error wrapping up %s."), head_file);
 709 }
 710
 711 static void save_todo(struct commit_list *todo_list, struct replay_opts *opts)
 712 {
 713         const char *todo_file = git_path(SEQ_TODO_FILE);
 714         static struct lock_file todo_lock;
 715         struct strbuf buf = STRBUF_INIT;
 716         int fd;
 717
 718         fd = hold_lock_file_for_update(&todo_lock, todo_file, LOCK_DIE_ON_ERROR);
 719         if (format_todo(&buf, todo_list, opts) < 0)
 720                 die(_("Could not format %s."), todo_file);
 721         if (write_in_full(fd, buf.buf, buf.len) < 0) {
 722                 strbuf_release(&buf);
 723                 die_errno(_("Could not write to %s."), todo_file);
 724         }
 725         if (commit_lock_file(&todo_lock) < 0) {
 726                 strbuf_release(&buf);
 727                 die(_("Error wrapping up %s."), todo_file);
 728         }
 729         strbuf_release(&buf);
 730 }
 731
 732 static void save_opts(struct replay_opts *opts)
 733 {
 734         const char *opts_file = git_path(SEQ_OPTS_FILE);
 735
 736         if (opts->no_commit)
 737                 git_config_set_in_file(opts_file, "options.no-commit", "true");
 738         if (opts->edit)
 739                 git_config_set_in_file(opts_file, "options.edit", "true");
 740         if (opts->signoff)
 741                 git_config_set_in_file(opts_file, "options.signoff", "true");
 742         if (opts->record_origin)
 743                 git_config_set_in_file(opts_file, "options.record-origin", "true");
 744         if (opts->allow_ff)
 745                 git_config_set_in_file(opts_file, "options.allow-ff", "true");
 746         if (opts->mainline) {
 747                 struct strbuf buf = STRBUF_INIT;
 748                 strbuf_addf(&buf, "%d", opts->mainline);
 749                 git_config_set_in_file(opts_file, "options.mainline", buf.buf);
 750                 strbuf_release(&buf);
 751         }
 752         if (opts->strategy)
 753                 git_config_set_in_file(opts_file, "options.strategy", opts->strategy);
 754         if (opts->xopts) {
 755                 int i;
 756                 for (i = 0; i < opts->xopts_nr; i++)
 757                         git_config_set_multivar_in_file(opts_file,
 758                                                         "options.strategy-option",
 759                                                         opts->xopts[i], "^$", 0);
 760         }
 761 }
 762
 763 static int pick_commits(struct commit_list *todo_list, struct replay_opts *opts)
 764 {
 765         struct commit_list *cur;
 766         int res;
 767
 768         setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
 769         if (opts->allow_ff)
 770                 assert(!(opts->signoff || opts->no_commit ||
 771                                 opts->record_origin || opts->edit));
 772         read_and_refresh_cache(opts);
 773
 774         for (cur = todo_list; cur; cur = cur->next) {
 775                 save_todo(cur, opts);
 776                 res = do_pick_commit(cur->item, opts);
 777                 if (res) {
 778                         if (!cur->next)
 779                                 /*
 780                                  * An error was encountered while
 781                                  * picking the last commit; the
 782                                  * sequencer state is useless now --
 783                                  * the user simply needs to resolve
 784                                  * the conflict and commit
 785                                  */
 786                                 remove_sequencer_state(0);
 787                         return res;
 788                 }
 789         }
 790
 791         /*
 792          * Sequence of picks finished successfully; cleanup by
 793          * removing the .git/sequencer directory
 794          */
 795         remove_sequencer_state(1);
 796         return 0;
 797 }
 798
 799 static int pick_revisions(struct replay_opts *opts)
 800 {
 801         struct commit_list *todo_list = NULL;
 802         unsigned char sha1[20];
 803
 804         read_and_refresh_cache(opts);
 805
 806         /*
 807          * Decide what to do depending on the arguments; a fresh
 808          * cherry-pick should be handled differently from an existing
 809          * one that is being continued
 810          */
 811         if (opts->subcommand == REPLAY_RESET) {
 812                 remove_sequencer_state(1);
 813                 return 0;
 814         } else {
 815                 /*
 816                  * Start a new cherry-pick/ revert sequence; but
 817                  * first, make sure that an existing one isn't in
 818                  * progress
 819                  */
 820
 821                 walk_revs_populate_todo(&todo_list, opts);
 822                 if (create_seq_dir() < 0) {
 823                         fatal(_("A cherry-pick or revert is in progress."));
 824                         advise(_("Use --reset to forget about it"));
 825                         exit(128);
 826                 }
 827                 if (get_sha1("HEAD", sha1)) {
 828                         if (opts->action == REVERT)
 829                                 die(_("Can't revert as initial commit"));
 830                         die(_("Can't cherry-pick into empty head"));
 831                 }
 832                 save_head(sha1_to_hex(sha1));
 833                 save_opts(opts);
 834         }
 835         return pick_commits(todo_list, opts);
 836 }
 837
 838 int cmd_revert(int argc, const char **argv, const char *prefix)
 839 {
 840         struct replay_opts opts;
 841
 842         memset(&opts, 0, sizeof(opts));
 843         if (isatty(0))
 844                 opts.edit = 1;
 845         opts.action = REVERT;
 846         git_config(git_default_config, NULL);
 847         parse_args(argc, argv, &opts);
 848         return pick_revisions(&opts);
 849 }
 850
 851 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
 852 {
 853         struct replay_opts opts;
 854
 855         memset(&opts, 0, sizeof(opts));
 856         opts.action = CHERRY_PICK;
 857         git_config(git_default_config, NULL);
 858         parse_args(argc, argv, &opts);
 859         return pick_revisions(&opts);
 860 }